Retroviruses are ubiquitous in nature and have long been recognized as infectious cancer causing pathogens in animals. It was only in the last decade, however, that pathogenic human retroviruses were discovered. The human T lymphotropic viruses types I and II (HTLV 1 and HTLV 2) are causally associated with adult T-cell leukemia/lymphoma, while the human immunodeficiency viruses types I and II (HIV 1 and HIV 2) are the etiologic agents of AIDS - the modern plague. Clearly, these and other as yet uncharacterized retroviruses represent a considerable public health threat because their prevalence in the population appears to be increasing, as is their association with various diseases. Of particular concern is the fact that they are transmitted by contaminated blood and blood products, necessitating the implementation of screening procedures to ensure safety of the blood supply. Recent advances in molecular biology, such as the polymerase chain reaction (PCR), which facilitates in vitro amplification of DNA, create exciting new possibilities for DNA diagnostics. Our proposal has two major goals; the first is development of a PCR assay to amplify pol gene sequences in all known, as well as uncharacterized human retroviruses. This is feasible because the PCR primers are targeted to highly conserved regions of the pol gene; the second major goal is to automate the entire PCR assay to detect retroviruses, including the non-radioactive detection of the specifically amplified pol gene fragment. The long term goal is to perfect the assay to the point where it can be used in blood banks as a reliable, sensitive, simple, automated test for retrovirus contamination of blood and related products.